A prime number is a natural number, greater than one, that can only be divided by 1 and itself.
The number 1037520 can be evenly divided by 1 2 3 4 5 6 8 9 10 11 12 15 16 18 20 22 24 30 33 36 40 44 45 48 55 60 66 72 80 88 90 99 110 120 131 132 144 165 176 180 198 220 240 262 264 330 360 393 396 440 495 524 528 655 660 720 786 792 880 990 1,048 1,179 1,310 1,320 1,441 1,572 1,584 1,965 1,980 2,096 2,358 2,620 2,640 2,882 3,144 3,930 3,960 4,323 4,716 5,240 5,764 5,895 6,288 7,205 7,860 7,920 8,646 9,432 10,480 11,528 11,790 12,969 14,410 15,720 17,292 18,864 21,615 23,056 23,580 25,938 28,820 31,440 34,584 43,230 47,160 51,876 57,640 64,845 69,168 86,460 94,320 103,752 115,280 129,690 172,920 207,504 259,380 345,840 518,760 and 1,037,520, with no remainder.
Since 1,037,520 cannot be divided by just 1 and 1,037,520, it is not a prime number.